This study looks at what degree patients with Klinefelter syndrome suffer from dyslexia, behavioral and learning disabilities and if testosterone replacement therapy alters these disabilities.Hypogonadal patients with Klinefelter syndrome undergo detailed neuropsychological testing before/after testosterone treatment Men enrolled in the study also have blood drawn for the establishment of lympho-blastoid cell lines, with the goal being to examine genetic differences in the x chromosome to see their impact on severity of the neuropsychology.